The biggest military exercise in eastern Europe since the Cold War kicked off in earnest Tuesday as roughly 2,000 NATO paratroopers were set to fill the skies over Poland.

The operation, called Anakonda 2016, is billed as a Polish-led training exercise and will span roughly 10 days. More than 30,000 troops from 24 different countries, including non-NATO states such as Finland and Kosovo, are set to participate in a series of events spread across Poland. The exercise is designed to emulate a “joint defensive operation on a large scale,” according to a release by the U.S. Army.

U.S. Army soldiers assigned to Charlie Co., 1st Squadron, 91st Cavalry Regiment and Alpha Battery, 319th Field Artillery Regiment, participate in an airborne operation during Anakonda 2016 in Drawsko Pomorskie, Poland, on June 6. (U.S. Army)

Components of Anakonda 2016 include live-fire training, the deployment of air defenses, bridging operations across the Vistula river, operating in an electronic warfare environment and unspecified “cyber” operations, according to the Army release. Anakonda will also pull in resources from two other training exercises occurring simultaneously in the region called Saber Strike 16 and Swift Response 16.

The exercise has been highly publicized with countries taking to social media to broadcast their participation.

“The United States Army and the United States military and really the United States of America have a single purpose in Operation Anakonda,” Gen. Mark Milley, the U.S. Army’s chief of staff, said Monday at the exercise’s opening ceremony. “And that is to bring all of us together to demonstrate that we are shoulder to shoulder with the Polish people, we are shoulder to shoulder with the Polish Army and we are shoulder to shoulder with NATO to ensure that all the countries of NATO remain free and independent.”

Meanwhile, adjacent to Anakonda, a large-scale amphibious exercise, known as Baltops 2016 is underway in the Baltic Sea. Now in its 44th year, Baltops 2016 began on June 4 and includes 17 countries and more than 6,000 troops.

Anakonda and Baltops 2016 are scheduled just weeks before NATO’s July summit in Warsaw, where it is expected that NATO will agree to deploy almost 5,000 troops from Britain, the United States and Germany to Poland. Polish President Andrzej Duda, in light of recent Russian activity in the region, has been calling for a permanent NATO presence in Poland since January.

A soldier participates in Anakonda 2016 at the training ground in northwestern Poland on June 4. (Marcin Bielecki/European Pressphoto Agency)

Anakonda’s size and location has already rankled some officials in Russia, with Russian Foreign Minister Sergei Lavrov telling his Finnish counterpart Monday that his country would respond to NATO and the United States’ increased activity in the Baltic region, though he did not go into specifics.

Since Russia annexed Crimea in 2014 and helped prop up separatists in eastern Ukraine, it has slowly ratcheted up military activity on its borders and repeatedly entered NATO airspace at levels not seen since the Cold War. In April, two Russian Su-24 strike fighters buzzed a U.S. destroyer in the Baltic Sea, and weeks later another flight of Russian jets intercepted an American reconnaissance aircraft flying near the Russian naval port in Kaliningrad, though the plane was in international airspace.

NATO and the United States have attempted to stymie Russian activity by increasing the number of training exercises in Europe and creating NATO task forces that are designed to respond to threats modeled after Russia’s approach in eastern Ukraine. The United States has also increased its deployments to Europe and positioned equipment throughout region in case it needs to rapidly deploy more units.